Re: tcpip-forward requests and bind addresses

[der Mouse <mouse%Rodents.Montreal.QC.CA@localhost>]

> [new proposed text]
[edited down -dM]
>    The address SHOULD be "" if connections are to accepted from anywhere
>    on all protocol families supported by the SSH implementation.  The
>    strings "0.0.0.0" and "::" SHOULD be used to listen on all interfaces
>    on only IPv4 or IPv6 respectively.

I think SHOULD is the wrong word to use here.  What we are doing is
saying "as a special case, this string is defined to have this
semantic".  This is not a SHOULD any more than any of the other defined
semantics is.  The whole document is implicitly covered by an
"implementations SHOULD implement these esmantics", after all.

>    The server SHOULD treat an 'address to bind' of "localhost" to be a
>    special case meaning to listen on all supported protocol families on
>    its loopback interfaces only.  Similarly, the numerically assigned
>    loopback strings of "127.0.0.1" [RFC3330] or "::1" [RFC3515] SHOULD be
>    used to listen on the loopback interface with only IPv4 or IPv6
>    respectively.

Here, the first SHOULD at least makes sense, though what it's really
doing is to define yet another special-case semantic.  The second one
here is in the same situation as the SHOULDs of the other paragraph
above.

I don't think the SHOULD/MUST/MAY language is appropriate here.  I'd
word this something like

    Some strings have special-case semantics: "" as an address to bind
    means that connections are to be accepted from anywhere on all
    protocol families supported by the SSH implementation.  "0.0.0.0"
    means to listen on all IPv4 addresses [note: not "interfaces"; the
    mapping between intefaces and addresses can be multi-valued in
    either direction].  "::" means to listen on all IPv6 addresses.
    "localhost" means to listen on all supported protocol families on
    loopback addresses only.  "127.0.0.1" and "::1", while not really
    special cases for a normally configured system [RFC3330] [RFC3515],
    indicate listening on the loopback interfaces for IPv4 and IPv6
    respectively.

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